Clockmaker’s Sector


A large nineteenth century brass clockmaker’s sector, with the name Edwin Herrick engraved on the back of the hinge.

The instrument is probably of English manufacture.  The sector is a proportional gauge and was used principally for the rapid sizing of wheels and pinions. It can also be used for sizing spring barrels and their arbors.

Detailed information on the construction and use of the sector is given in The Watch & Clock Makers’ Handbook Dictionary and Guide by F. J. Britten.

An Edwin Herrick is recorded as a clockmaker at Myddleton Street, Clerkenwell, and London between 1867 and 1871.

The sector is 26 inches long and retains much of its original lacquer.

The pinion sizing section of the scale is graduated 6,7,8,10, then at 2 unit intervals to 24.

The wheel sizing scale is graduated from 25 to 190 at one unit intervals.


This shows the back of the hinge where the engraved name of Edwin Herrick appears.


Stock No. C1123

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